It is well known in the art to employ various square planar transition metal complexes deposited on various electrodes to catalyze the electrocatalytic reduction of carbon dioxide. One example is disclosed in a journal article by Kapusta et al entitled "Carbon Dioxide Reduction at a Metal Phthalocyanine Catalyzed Carbon Electrode" in the Journal of the Electrochemical Society (1984) wherein it is disclosed that metal phthalocyanines deposited to a thickness of 10 .mu.g/cm.sup.2 on a carbon electrode which is them immersed in a neutral solution will catalyze the electrochemical reduction of carbon dioxide to formic acid.
Another journal article is "Catalytic Reduction of CO.sub.2 at Carbon Electrodes Modified with Cobalt Phthalocyanine" in the Journal of the American Chemical Society (1984) by Lieber et al which disclosed that the electrocatalytic reduction of carbon dioxide was improved by the monolayer coverage of cobalt phthalocyanine on the carbon electrode. The reduction of carbon dioxide to carbon monoxide at a pH of 5 was said to proceed at a turnover rate of 50 s.sup.-1.
The use of cyclam complexes is disclosed in a journal article by Beley et al entitled "Nickel(II)-Cyclam: An Extremely Selective Electrocatalyst for Reduction of CO.sub.2 in Water" in the Journal of the Chemical Society, Chemical Communications (1984) wherein it is disclosed that nickel(II) cyclam complexes display a high selectivity for the electrocatalytic reduction of carbon dioxide to carbon monoxide in an aqueous solution having a pH of 4.1. However, the turnover rate is disclosed as only being 32 hr.sup.-1.
The employment of nickel and cobalt macrocyclic compounds is disclosed in a journal article by Fisher et al entitled "Electrocatalytic Reduction of Carbon Dioxide by Using Macrocycles of Nickel and Cobalt" in the Journal of the American Chemical Society (1980) wherein it is disclosed that macrocyclic compounds can be utilized to catalyze the electrocatalytic reduction of carbon dioxide to carbon monoxide in aqueous and mixed aqueous/nonaqueous solvents at a mercury electrode.
Finally, an overview of several different carbon dioxide reduction methods is disclosed in an article "Fuel from CO.sub.2 : An Electrochemical Study" in CHEMTECH (1984) by Ulman et al with relevant discussion being directed toward the use of porphyrins and mercury, zinc, tin, indium, lead and carbon cathodes to improve carbon dioxide reduction.